ALAsset中的Photo的方向行为不正确 [英] Orientation does not behave correctly with Photo in ALAsset

问题描述

我目前有一个使用ALAsssetsLibrary来获取照片的应用。我已将照片放置在图像视图中，我可以上传到服务器。当我在拍摄一些照片后在真实设备上进行测试时，我发现应该在肖像中拍摄的照片变成风景。

I current have an app that uses ALAsssetsLibrary to fetch the photos. I have placed the photo to an image view and I am able to upload to the server. When I tested on the real device after taking some photos, I found out the photos that supposed to be taken in Portrait become a landscape.

因此，我调用了不同的功能得到这样的CGImage：

Therefore, I called different function to get the CGImage like this:

UIImage *image = [UIImage imageWithCGImage:[representation fullResolutionImage] scale:1.0 orientation:(UIImageOrientation)[representation orientation]];

第一次试用，我用过这个：

The first tried out, I used this :

UIImage *image = [UIImage imageWithCGImage:[representation fullResolutionImage]]

我认为那个有刻度和方向的那个可以给我正确的方向照片拍摄。但它没有给我正确的解决方案。

I thought the one with scale and orientation could give me the right orientation that the photo was taken. But it didn't give me the right solution.

我是否错过了生成正确照片方向所需的任何内容？

Do I miss anything that is necessary to generate a correct orientation of photo?

推荐答案

正确的方向处理取决于您使用的iOS版本。
在iOS4和iOS 5上，缩略图已经正确旋转，因此您可以在不指定任何旋转参数的情况下初始化UIImage。
但是对于fullScreenImage，每个iOS版本的行为都不同。在iOS 5上，图像已经在iOS 4上旋转了。

The correct orientation handling depends on the iOS version you are using. On iOS4 and iOS 5 the thumbnail is already correctly rotated, so you can initialize your UIImage without specifying any rotation parameters. However for the fullScreenImage, the behavior is different for each iOS version. On iOS 5 the image is already rotated on iOS 4 not.

所以在iOS4上你应该使用：

So on iOS4 you should use:

ALAssetRepresentation *defaultRep = [asset defaultRepresentation];
UIImage *_image = [UIImage imageWithCGImage:[defaultRep fullScreenImage] 
                                                     scale:[defaultRep scale] orientation:(UIImageOrientation)[defaultRep orientation]];

在iOS5上，以下代码应该可以正常工作：

On iOS5 the following code should work correctly:

ALAssetRepresentation *defaultRep = [asset defaultRepresentation];
UIImage *_image = [UIImage imageWithCGImage:[defaultRep fullScreenImage] scale:[defaultRep scale] orientation:0];

干杯，

Hendrik

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